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<head><meta charset="utf-8"><title>Turning on binder validation in rustc · wg-traits · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/index.html">wg-traits</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/Turning.20on.20binder.20validation.20in.20rustc.html">Turning on binder validation in rustc</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/Turning%20on%20binder%20validation%20in%20rustc/near/240051032" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/Turning.20on.20binder.20validation.20in.20rustc.html#240051032">(May 24 2021 at 13:30)</a>:</h4>
<p>So, I was chatting with <span class="user-mention" data-user-id="116009">@nikomatsakis</span> in PMs about possible turning on the binder validation logic in rustc on nightly for like a week. I'll copy some of those messages here, in case others want to discuss</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/Turning%20on%20binder%20validation%20in%20rustc/near/240051143" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/Turning.20on.20binder.20validation.20in.20rustc.html#240051143">(May 24 2021 at 13:31)</a>:</h4>
<p>Well, might be easier to just summarize:</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/Turning%20on%20binder%20validation%20in%20rustc/near/240051487" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/Turning.20on.20binder.20validation.20in.20rustc.html#240051487">(May 24 2021 at 13:33)</a>:</h4>
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<li>The biggest downside of turning it on is the (likely) big perf hit (it's currently only in debug builds)</li>
<li>We should probably add a <code>-Z validate-bound-vars</code> flag or something that's <em>opt-in</em>, and announce it in a blog post</li>
<li>This blog post would be a good time to also discuss "GATs are no longer incomplete" (when we get there), TAIT, etc.</li>
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<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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